The present invention relates generally to stators for vehicle dynamo-electric machines and, in particular, to a stator assembly for a dynamoelectric machine with clips that accept radial insertion of square wire.
Dynamoelectric machines, such as electric motors, or alternators are well-known. Alternators typically are composed of a stator assembly fixedly supported by an alternator housing and a rotor assembly supported coaxially within the stator assembly. The stator assembly includes a generally cylindrically-shaped stator core having a plurality of core slots formed along the inner surface thereof and a stator coil disposed in the core slots. The core slots define a plurality of teeth therebetween. The teeth are connected to the core by a yoke portion.
The stator coil is formed by connecting a plurality of wires wound thereon, forming stator windings. The stator windings are accommodated at the plurality of core slots in a plurality of radially extending layers, and are formed of straight portions that are located in the core slots and of end loop sections that connect two adjacent straight portions and are formed in a predetermined multi-phase (e.g. three or six) winding pattern in the slots of the stator core.
It is known in the art that in order to increase the output and efficiency of an alternator it is desirable to have stator winding conductors of rectangular-shaped cross sections that are aligned in a radial row in each core slot and whose widths, including any insulation, closely fit to the width of the core slots. This is advantageous because the larger conductor width reduces the electrical resistance of the stator winding, and therefore reduces the stator conductor power losses. It is also known in the art to provide a stator core with small slot openings at the inner diameter of the core, which reduces the effective air gap are to increase the alternator output. A smaller slot opening also reduces the fluctuation of magnetic flux on the rotor pole surface which reduces eddy current losses on the rotor pole and therefore increases alternator efficiencies. It is also desirable to ease manufacturing of the stator assembly by having continuous rectangular shaped conductors to eliminate any weld operation required to connect individual U-shaped conductors axially inserted in the core slot openings. However, these desirable features lead to a design contradiction in that the conductors must be large to lower the electrical resistance, must also fit closely to the width of the core slots, and must be continuous conductors, but cannot be inserted into the core slots from a radially inward position through a smaller core opening.
Prior art remedies typically attempted to resolve this design contradiction by utilizing continuous conductors that are small enough to enter the slot openings but do not closely fit the width of the slot. These prior art remedies result in large voids and low slot fill factors, which leads to an alternator with low output and efficiency. Other prior art remedies utilize U-shaped conductors, which are axially inserted into the core slots and then welded together to form the finished stator windings. These other prior art remedies manage to accomplish a high slot fill factor and consequently low resistance, but encounter difficulties in the assembly of multiple insertions and welds.
In view of the above discussed problems, it is advantageous to provide a stator having core slots that allow for conductors that fit closely to the width of the core slots and that allow the conductors to be inserted into the core slots from a radially inward position while also providing a smaller core opening. As a result, an alternator having high output and high efficiency while also being easy to assemble and manufacture is realized.